Łódź is a city in central Poland and a former industrial centre. It is the capital of Łódź Voivodeship, and is located 120 km (75 mi) south-west of Warsaw. As of 2024,^[update] Łódź has a population of 645,693, making it the country's fourth largest city.

Łódź first appears in records in the 14th century. It was granted town rights in 1423 by the Polish King Władysław II Jagiełło and it remained a private town of the Kuyavian bishops and clergy until the late 18th century. In the Second Partition of Poland in 1793, Łódź was annexed to Prussia before becoming part of the Napoleonic Duchy of Warsaw; the city joined Congress Poland, a Russian client state, at the 1815 Congress of Vienna. The Second Industrial Revolution (from 1850) brought rapid growth in textile manufacturing and in population owing to the inflow of migrants, a sizable part of which were Jews and Germans. Ever since the industrialization of the area, the city had been multinational and struggled with social inequalities, as documented in the novel The Promised Land by Nobel Prize–winning author Władysław Reymont. The contrasts greatly reflected on the architecture of the city, where luxurious mansions coexisted with red-brick factories and dilapidated tenement houses.

The industrial development and demographic surge made Łódź one of the largest cities in Poland. During the interwar period, Łódź became an important center for the Polish artistic avant-garde. Founded in 1931, Muzeum Sztuki became the first museum in Europe dedicated to collecting and showcasing modern art. Under the German occupation during World War II, the city's population was persecuted and its large Jewish minority was forced into a walled zone known as the Litzmannstadt Ghetto, after the Nazi German renaming of the city, from where they were sent to German concentration and extermination camps. The city became Poland's temporary seat of power in 1945.

Łódź experienced a sharp demographic and economic decline after 1989. It was only in the 2010s that the city began to experience revitalization of its neglected downtown area. Łódź is ranked by the Globalization and World Cities Research Network on the "Sufficiency" level of global influence. The city is internationally known for its National Film School, a cradle for the most renowned Polish actors and directors, including Andrzej Wajda and Roman Polański. In 2017, the city was inducted into the UNESCO Creative Cities Network and named UNESCO City of Film.

There is no consensus on the origin of the city's name. The Polish word łódź means 'boat', but popular theories link it with the medieval village of Łodzia and the now-canalised River Łódka on which the modern city was founded. It may also be related to łoza 'willow tree' or the Old Polish personal name Włodzisław.

Łódź first appears in a 1332 written record issued by Władysław the Hunchback, Duke of Łęczyca, which transferred the village of Łodzia to the Bishopric of Włocławek. The document enumerated the privileges of its inhabitants, notably the right to graze land, establish pastures and engage in logging. In 1423, King of Poland Władysław II Jagiełło officially granted town rights to the village under Magdeburg Law. For centuries, it remained a small remote settlement situated among woodlands and marshes, which was privately held by the Kuyavian bishops. It was administratively located in the Brzeziny County in the Łęczyca Voivodeship in the Greater Poland Province of the Kingdom of Poland. The economy was predominantly driven by agriculture and farming until the 19th century. The earliest two versions of the coat of arms appeared on seal emblems in 1535 and 1577, with the latter illustrating a boat-like vessel and a turned oar.

With the Second Partition of Poland in 1793, Łódź was annexed by Prussia. In 1798, the Kuyavian bishops' ownership over the region was formally revoked during the secularisation of church property. The town, governed by a burgomaster (burmistrz), at the time had only 190 residents, 44 occupied dwellings, a church and a prison. In 1806, Łódź was incorporated into the Napoleonic Duchy of Warsaw. In the aftermath of the 1815 Congress of Vienna, the duchy was dissolved and the town became part of the Congress Kingdom of Poland, a client state of the Russian Empire.

In 1820, the government of the Congress Kingdom designated Łódź and its rural surroundings for centrally planned industrial development. Rajmund Rembieliński, head of the Administrative Council and prefect of Masovia, became the president of a commission that subdivided the works two major phases; the first (1821–23) comprised the creation of a new city centre with an octagonal square (contemporary plac Wolności; Liberty Square) and arranged housing allotments on greenfield land situated south of the old marketplace; the second stage (1824–28) involved the establishment of cotton mill colonies and a linear street system along with an arterial north–south thoroughfare, Piotrkowska. Many of the early dwellings were timber cottages built for housing weavers (domy tkaczy).